Mutiny Pagination does not init if only one iteration

[flamurjahiri]

When using Mutiny Pagination API, if the condition is fullfilled first time, it does not emit value anymore (when using until), but when i use whilst it emits item

Reproduction :

https://github.com/flamurjahiri/Mutiny---Emit-on-Until

Im not sure if this is desired to work like that, or its an issue

[flamurjahiri]

https://github.com/flamurjahiri/Mutiny---Emit-on-Until/blob/main/src/main/java/io/kodelabs/ExampleResource.java direct reproduction link

[flamurjahiri]

@jponge , have you had the chance to check if this should behave like this

[jponge]

This is expected, repeating with until and whilst has different semantics. Here are the relevant operator implementations, this should make sense.

In the case of until, the operator looks like:

@Override
public void onItem(T t) {
    try {
        passed = !predicate.test(t);
    } catch (Throwable failure) {
        cancel();
        downstream.onFailure(failure);
        return;
    }
    if (passed) {
        emitted++;
        downstream.onNext(t);
    }
}

So if the predicate is false, we don't push the item downstream.

The whilst operator is different:

@Override
public void onItem(T t) {
    try {
        stop = !predicate.test(t);
    } catch (Throwable failure) {
        cancel();
        downstream.onError(failure);
        return;
    }
    emitted++;
    downstream.onNext(t);
}